Conventionally, an ejector refrigeration cycle device is known to be a vapor compression refrigeration cycle device including an ejector as a refrigerant decompression portion.
In this kind of ejector, a high-pressure refrigerant is isentropically decompressed by and injected from a nozzle portion. By the suction effect of the injection refrigerant, another refrigerant is drawn from an outlet side of an evaporator, thereby recovering the loss of kinetic energy caused when decompressing the refrigerant at the nozzle portion. The recovered energy (recovery energy) is converted to pressure energy in a diffuser (pressurizing portion) of the ejector, thereby pressurizing the refrigerant. Note that the recovery energy is sometimes called expansion energy.
Furthermore, in the ejector refrigeration cycle device, the refrigerant pressurized by the diffuser is guided to a suction side of a compressor, thereby making it possible to increase the pressure of the suction refrigerant to a higher level than in a normal refrigeration cycle device in which a refrigerant evaporation pressure in an evaporator becomes substantially equal to a pressure of the suction refrigerant drawn into the compressor. Thus, the ejector refrigeration cycle device can reduce the power consumption by the compressor to improve a coefficient of performance (COP) of the cycle, compared with the normal refrigeration cycle device.
Patent Document 1 discloses an ejector refrigeration cycle device that includes an ejector with a swirl space as a swirl-flow generating portion for causing a swirling flow in a subcooled liquid-phase refrigerant flowing into a nozzle portion.
In the ejector disclosed in Patent Document 1, the subcooled liquid-phase refrigerant is swirled in the swirl space to decompress and boil the refrigerant on a swirl center side, so that the refrigerant is converted into a two-phase separated state that contains a larger amount of the gas-phase refrigerant on the swirl center side rather than in an outer region of the swirl space. By allowing such a refrigerant in the two-phase separated state to flow into a nozzle passage (nozzle portion), the boiling of the refrigerant is promoted in the nozzle passage, thereby improving energy conversion efficiency when converting the pressure energy of the refrigerant to kinetic energy in the nozzle passage.